<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>表格</title>
</head>
<!-- tr是行，td是列，th是表头（标题） -->
<!-- colspan是跨列，rowspan是跨行 -->

<body>
    <h1>2020年12月</h1>
    <form action="#" method="POST">
        <table border="2">
            <tr>
                <th>一</th>
                <th>二</th>
                <th>三</th>
                <th>四</th>
                <th>五</th>
                <th>六</th>
                <th>日</th>
            </tr>
            <tr>
                <td style="color: dimgrey;">30</td>
                <td>1</td>
                <td>2</td>
                <td>3</td>
                <td>4</td>
                <td>5</td>
                <td>6</td>
            </tr>
            <tr>
                <td>7</td>
                <td>8</td>
                <td colspan="3">9</td>
                <td rowspan="3">10</td>
                <td>11</td>
                <td>12</td>
                <td>13</td>
            </tr>
            <tr>
                <td>14</td>
                <td>15</td>
                <td>16</td>
                <td>17</td>
                <td>18</td>
                <td>19</td>
                <td>20</td>
            </tr>
            <tr>
                <td>21</td>
                <td>22</td>
                <td colspan="3" rowspan="3">23</td>
                <td>24</td>
                <td>25</td>
                <td>26</td>
                <td>27</td>
            </tr>
            <tr>
                <td>28</td>
                <td>29</td>
                <td>30</td>
                <td>31</td>
            </tr>
        </table>
    </form>
</body>

</html>